In a multi-cylinder internal combustion engine there is a systematic error in the injection of fuel into the combustion chambers, due to variations, in particular, in the mechanical properties of the injection device, for example of the injectors in diesel engines with a common rail. The manufacturing tolerances for the components mentioned (different idle strokes) mean that, when actuated for the same length of time and with the same actuation energy, different quantities of fuel for combustion are fed to the individual cylinders. The different quantities of fuel lead to different power outputs from the individual cylinders which, apart from raising the running irregularity, also leads to an increase in the quantity of harmful exhaust gas components. In addition, differences in the idle stroke can invoke changes in the opening characteristics of the injectors. This manifests itself by differences in the start of the hydraulic injection between the individual injectors, and in the time-trace of the injection.
The underlying object of the invention is to specify a method of the type mentioned in the introduction which permits the actual systematic errors, which depend on the injection parameters, relevant for balancing out the cylinders to be determined in a simple way in terms of the injection quantities, the start of the hydraulic injection and the time-trace of the injection.